Simple Tutorial wanted on CALayers

I can't seem to wrap my head around using CALayer's to sublayer themselves creating duplicate, smaller images that are to be in an animation later. I can create using CGImage, and I can assign CGImageRef's to a layer, but this is the part that I'm having trouble with: I want to make an animation where one half of the image goes one, say left, and the other goes right. Essentially, I want to have two layers, say left half and right half, then create a CAAnimation with or without CATransaction, whichever's lowest-level, and tell it to "open the image". It's to the point where I am willing to pay for this information. I keep wanting to manually break the CGImage up using ImageInRect, start a timer, and animate it myself as if it were a sprite in any other game... in that respect, I have some skill. But for some reason, the CALayer stuff just isn't clicking. I'm looking to find, or have someone make, a tutorial explaining how to "Split the image up, and animate the sections separately". The end result is something similar to the youtube video of "Core animation shutter transition example" if you can find it. Don't worry about making it as complex as his. I just need a simple "How to grab the layer, take separate sections, start the animation". I do not believe it would go in drawRect:, but I could be wrong. The goal is to use CALayer's animation instead of manually drawing CGLayers. So far, no internet tutorial has a clear how-to as far as this depth. And the books I find don't illustrate using animation on separated layers from one layer, then they skip a subject or two. Finding a tutorial that explains this will also count, but it must be clear to me.